1. Field of the Invention
The present invention relates to a method for controlling the temperature of a printing unit by means of a temperature control medium.
In order to control the temperature of printing units or devices located therein, for example rolls, water is normally used.
It has become known, for example, from German patent DE 195 02 475 C2 (corresponding to U.S. Pat. No. 5,823,108) to use lubricant instead of water as a temperature control medium for the ductor roll of a printing unit.
2. Summary of the Invention
It is an object of the invention to provide a further temperature control method in a printing machine and also to provide a press that is suitable for the implementation of the novel method.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for controlling a temperature of a first printing unit, the method which comprises:                conducting dampening solution from a second printing unit; and        utilizing the dampening solution from the second printing unit as a temperature control medium for controlling the temperature in the first printing unit.        
In the method according to the invention, dampening solution which originates from another printing unit is used to control the temperature of the printing unit to be tempered. The dampening solution is therefore used multi-functionally; in one printing unit as a dampening solution per se and in the other printing unit as a temperature control medium. As a result, the construction of the press comprising the printing units is simplified. For example, the number of pumps needed is reduced. No additional temperature control medium pump is required and only one dampening solution pump is sufficient.
Various developments of the method according to the invention are possible, some will be explained briefly in the following text.
In one development, the printing unit in which the dampening solution is used as such and which, in the following text, will be designated the second printing unit, is a lithographic printing unit, that is to say a planographic printing unit. In this case, the other printing unit, which, in the following text, will be designated the first printing unit and in which the dampening solution is used as a temperature control medium, is not such a planographic printing unit. Accordingly, the two printing units are constructed differently from each other with respect to their printing process.
In a further development, the second printing unit is an offset printing unit and the first printing unit is a flexographic printing unit, for example used for spot varnishing.
In a further development, the first printing unit is a varnishing unit, for example used for full-surface varnishing.
According to a further development, by means of a temperature controller, temperatures of the dampening solution and temperature control medium which are different from the first printing unit to the second printing unit are set.
In this case, according to a further development, the dampening solution and temperature control medium can have its temperature controlled so as to be warmer in the first printing unit than in the second printing unit.
In a further development, the aforesaid temperature controller is an additional auxiliary temperature controller comprised by the press in addition to a central main temperature controller. The auxiliary temperature controller and the main temperature controller are incorporated in one and the same circuit of the dampening solution and temperature control medium.
Further developments contain different embodiments of the aforesaid auxiliary temperature controller. For example, the auxiliary temperature controller can have a mixing valve which branches off a partial quantity of the dampening solution and temperature control medium flowing back from the first printing unit in a return line and feeds this partial quantity into a feed line in which the dampening solution and temperature control medium flows to the first printing unit. Likewise, the auxiliary temperature controller can have a heat exchanger, via which the aforesaid return line is coupled thermally to the aforesaid feed line.
According to further developments, which can also be used in combination with one another, the temperature control of the first printing unit can be carried out in the following manner: the dampening solution and temperature control medium can be led through a roll and/or a trough belonging to the first printing unit. This roll can be, for example, an engraved roll or a dip roll. It is also possible to lead the dampening solution and temperature control medium to a heat exchanger, which couples a circuit for the printing ink processed in the first printing unit or the varnish processed therein thermally with that circuit in which the dampening solution and temperature control medium is circulated.
In a further development, the dampening solution is used as a coolant in the first printing unit. This is advantageous in particular when a solvent-based printing ink or a solvent-based varnish, such as a varnish emulsion with water as solvent, is printed in the first printing unit. Printing inks and varnishes of this type require cooling in many applications, in particular if they are pigmented printing inks or varnishes, metallures or iriodines.
The invention also includes a press which, on account of its construction, is suitable for the implementation of the method according to the invention or one of its developments.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a temperature control method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.